Microwave oven door

ABSTRACT

An improved door for microwave ovens having no exposed nut and bolt type means to retain the various components of such door together. The door is so constructed that the method for taking the door apart is not readily apparent to the average microwave oven user. Various components are mounted on the interior housing panel and various other components are mounted on the exterior housing panel. Then the interior housing panel and the exterior housing panel and their associated respective components are mounted together by concealed retaining means.

United States ?atent n91 Jarvis et a1.

[ MICROWAVE OVEN DOOR [75] Inventors: George A. Jarvis; Allen M. Danley,

both of Minneapolis, Minn.

[73] Assignee: Litton Systems, Inc., Beverly Hills,

' Calif.

[22] Filed: Nov. 15, 1971 [21] Appl. No.: 198,750

[52] US. Cl. ..2l9/10.55, 24/201 S, 126/190 [51] Int. Cl. ..H05b 9/06 [58] Field of Search ..219/10.55; 24/73 SC,

24/73 HS, 201 S; 126/190 1 [56] 4 References Cited UNITED STATES PATENTS Herr et a1. ..24/73 HS Von Rath ..24/73 HS 51 May 1, 1973 7/1906 Svenson 24/201S 2/1969 Tingley..... ..219/10 55 Primary ExaminerJ. V. Truhe Assistant ExaminerHugh D. Jaeger Attorney-Franklin D. Jankosky et a1.

[ 5 7 ABSTRACT An improved door for microwave ovens having no exposed nut and bolt type means to retain the various components of such door together. The door is so constructed that the method for taking the door apart is not readily apparent to the average microwave oven user. Various components are mounted on the interior housing panel and various other components are mounted on the exterior housing panel. Then the interior housing panel and the exterior housing panel and their associated respective components are mounted together by concealed retaining means.

5 Claims, 5 Drawing Figures Patented May 1, 1973 2 Sheets-Sheet 2 GEORGE A. JARV/S ALLE/V M. DA/VLE) O. gWL/ ATTORNEY MICROWAVE OVEN DOOR FIELD OF THE INVENTION This invention relates to microwave ovens and more particularly to an improved doorfor such microwave ovens.

DESCRIPTION OF THE PRIOR ART It is well-known that foodstuffs may be cooked within a microwave oven by electromagnetic wave energy radiating from a magnetron. The conventional microwave oven has a rectangular, box-like cooking cavity in which foodstuffs may be placed for exposure to such electromagnetic wave energy. The cooking cavity generally is constructed of six walls, one of the walls being the interior surface of the microwave oven door. The door facilitates the insertion and the removal of the foodstuffs to and from the cooking cavity of the microwave oven. Any time a door is utilized to seal an opening, there is some clearance between the edges of the door and the abutting edges defining the opening, the width of the clearance being dependent upon the tolerance of the particular construction. 1

In a microwave oven, such a clearance provides a path for the escape of electromagnetic wave energy from the cavity of the microwave oven. Excessive leakage of electromagnetic wave energy may be harmful to persons in close proximity of the microwave oven and may interfere with other communications systems. To prevent excessive leakage of electromagnetic wave energy from the microwave ovens, the manufacturers of such ovens provide electromagnetic wave energy seals either in the door or within the surface abutting the door in the closed position.

Various types of microwave oven doors have been manufactured in the past, including doors which do not include a viewing area to allow one to observe the cooking of foodstuffs. Practically all of the modern microwave ovens include a conventional RF screen through which one is able to observe the cooking of foodstuffs placed within the cavity of the microwave oven. Typically, a pane of transparent material, such as glass or plastic, is placed on either side of the RF screen, or the RF screen is sandwiched between two such panes of transparent material. Thus, it is evident from the above description of a typical microwave oven door that such microwave oven doors are of more sophisticated construction than the ordinary front door of ones house.

Over a period of continuous use of the microwave oven, moisture and food particles will adhere to the interior surface of the microwave oven door and may enter the internal areas of the door. A typical fastidious housewife desires a spotless microwave oven and she will consistently clean the cavity of the microwave oven, including the interior surface of the microwave oven door. However, because of the mechanical aspects of the microwave oven door construction, she may call upon her husband to take the door apart in order that she may clean the internal areas of the door. Since the various components of prior microwave oven doors were held together by conventional exposed nut and bolt type means, the husband could successfully take apart the door with ordinary household tools, for example, a screw driver and/or a pair of pliers. The husband could usually reconstruct the microwave oven door without any visual damage thereto. However, if the husband was not extremely careful in reconstructing the microwave oven door, the effectiveness of the door seal was usually impaired with the resultant possibility that the husband and wife would be exposed to excessive electromagnetic wave energy. On the other hand, if the husband did any visual damage to the microwave oven door, he would contact a qualified microwave oven repair man who would fix or replace the damaged component at considerable cost in order to repair the effectiveness of the electromagnetic wave energy seal.

Accordingly, it is an object of the present invention to provide an improved microwave oven door of rigid construction having no exposed nut and bolt type means.

, It is a further object of the present invention to provide an improved microwave oven door that would discourage the average microwave oven user from attempting to take the microwave oven door apart.

It is a still further object of the present invention to provide an improved microwave oven door which cannot be readily taken apart by the average microwave oven user employing ordinary household tools without causing visual damage to the microwave oven door.

It is another object of the present invention to provide an improved microwave oven door which may be readily taken apart by a qualified microwave oven repair man having the necessary tool and technical know-how.

SUMMARY OF THE INVENTION In accordance with the objects set forth above, the present invention provides an improved door for microwave ovens having no exposed nut and bolt type means to retain the various components of .such door together. The door is so constructed that it cannot be readily taken apart by the average microwave oven user without causing visual damage to one or more components of the door. Various components are mounted on the interior housing panel and various other components are mounted on the exterior housing panel. Then the interior housing panel and the exterior housing panel and their associated respective components are mounted together by concealed retaining means.

BRIEF DESCRIPTION OF THE DRAWINGS Additional objects, advantages and characteristic features of the present invention will become readily apparent from the following detailed description of the preferred embodiment of the invention when taken in conjunction with the drawings, in which:

FIG. 1 is a perspective view of a microwave oven in accordance with the present invention;

FIG. 2 is an elevational view of the interior side of the microwave oven door in accordance with the present invention;

FIG. 3 is a side elevational view of the microwave oven door taken along line 3-3 of FIG. 2 in accordance with the present invention;

FIG. 4 is an exploded view of the microwave oven door in accordance with the present invention; and

FIG. 5 is a perspective view of the concealed retaining means of the microwave oven door in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT magnetron. The exterior of the microwave oven is generally comprised of a housing 11, a door 12 and a control panel 13. The control panel 13 includes a conventional timer and an indicator light. The door 12 includes a viewing area 14 which consists of an RF screen sandwiched between two panes of glass which enables one to view the cooking of the foodstuffs placed within the cavity of the microwave oven 10.

Referring now to FIGS. 2 and 3, there are respectively shown an elevational view of the interior side of the microwave oven door 12 and a side elevational view of the microwave oven door 12. The microwave oven door 12 is generally comprised of a viewing area 14, a flexible seal plate 15, an inner housing panel 16, an outer housing panel 17, a choke filler 18 and a handle 19. As illustrated in FIGS. 1 through 3, the microwave oven door 12 does not include any exposed nut and bolt type means which would allow the user to take the microwave oven door apart for any purpose whatsoever with any ordinary household tool.

Referring now to FIG. 4, there is shown an exploded perspective view of the microwave oven door 12 illustrated in FIGS. 1 through 3. The microwave oven door is comprised of the following components: a handle 19, which may be constructed of die cast zinc and may be chrome-plated; an outer housing panel 17, which may be constructed of die cast zinc and may be partially chrome-plated and partially painted and includes a first plurality of studs 20 and a second plurality of studs 21; a first pane of transparent material 22, such as glass or plastic; a window mask assembly 23 consisting of four pieces of resilient sponge material strips; an inner housing panel 16 which includes an RF screen 24 and the choke filler 18 which is a continuous piece of suitable dielectric material, such as polypropylene, which is located within a recessed picture frame like area of the inner housing panel 16; a second pane of transparent material 25, such as, glass or plastic; a tecknit gasket 250, which is a resilient cylindrical-shaped fine wire mesh member; a flexible seal plate having a plurality of screws 26 conventionally welded to its inner surface; a pair of hinges 27 of suitable steel material which may be chrome-plated; a hinge connecting rod 28 which may be a V4 inch diameter steel .rod and may be chrome-plated;'a latching member 29 which may be heat-treated stamped steel and may be chrome-plated; and other associated components, including a plurality of spring steel clips 30, a plurality of retaining caps 31, a plurality of retaining clips 32, and a plurality of nuts In constructing the microwave oven door 12, the second pane of transparent material 25 may be placed against the RF screen 24 of the inner housing panel 16. The tecknit gasket 25a may be placed around the periphery of the second pane of transparent material 25. The tecknit gasket 25a provides a continuous electrical conducting path between the inner housing panel 16 and the seal plate 15 for preventing electromagnetic wave energy in the window area from traveling to the choke filler 18. The flexible seal plate 15 may then be aligned on the inner housing panel 16 by means of passing the plurality of weld screws 26 through a like plurality of openings 16a of the inner housing panel 16. A like plurality of nuts 33 may then be fastened to the respective plurality of screws 26 in order to retain the flexible seal plate 15 and the second pane of transparent material 25 to the inner housing panel 16. The four retaining clips 32 are placed on the four corner weld screws 26 prior to affixing the respective nuts 33. The pair of hinges 27 and the hinge connecting rod 28 may be assembled and may be placed within the pair of openings 16b; then such assembly may be mounted to the inner housing panel 16 by conventional means; (not illustrated). The latching member 29 may be placed within the pair of openings 16c and may be mounted to the inner housing panel 16 by conventional means (not illustrated).

The first pane of transparent material 22 may be placed on the outer housing panel 17 within the area defined by the six studs 20 and may be retained on the outer housing panel 17 by means of the six studs 20 and the six spring steel clips 20 which overlap the edges of the first pane of transparent material 22. The illustrated four pieces of the window mask assembly 23 may be pre-cemented together by conventional means and may then be aligned with the outer edges of the first pane of transparent material 22. The window masking assembly serves as a cushion between the firs pane of transparent material 22 and the inner housing panel 16 and further serves to mask the internal parts of the microwave oven door 12. The four retaining caps 31 may then be mounted to the four illustrated studs 21 of the outer housing panel 17 by means of an interference fit. Thus, the inner housing panel 16 and its mounted components and the outer housing panel 17 and its mounted components are ready for final assembly.

Referring now to FIG. 5, there is shown a perspective view of the concealed retaining means of the microwave oven door 12. Such concealed retaining means principally includes four retaining caps 31 and four retaining clips 32. As discussed earlier, the retaining caps 31 have previously been mounted to four studs 21 by means of an interference fit, and the four retaining clips 32 have been mounted to the four corner screws 26 by means of four of the nuts 33. In order to mount the inner housing panel 16 and its associated components to the outer housing panel 17 and its associated components, the distalends of the retaining clips 32 are forced over the retaining caps 31 to complete the construction of the microwave oven door 12. The concealed retaining means provides a secure and certain mounting of the inner housing panel 16 and its associated components to the outer housing panel 17 and its associated components so that such panels may not be readily separated by one not possessing the necessary technical know-how. The door handle 19 may then be placed on the center member 29a of the latching member 29 and may be retained thereon by means of a set screw (not shown).

In attempting to take apart the microwave oven door 12, the average microwave oven owner would probably attempt to wedge a screw-driver between the inner housing panel 16 and the outer housing panel 17, or possibly he may attempt to wedge a screwdriver under the flexible seal plate 15, in order to separate such panels. However, such actions could cause irreparable damage to the electromagnetic wave energy sealing capabilities of the door 12. On the other hand, the qualified microwave oven repairman will first take off the door handle 19 by loosening the aforementioned set screw. At this point the microwave oven door construction is intact for the purposes of the present invention. The repairman will then insert a'rod, or bar, of approximate 3/16 inch diameter into either one of the openings 16b of the inner housing panel 16. By proceeding to use the rod, or bar, as a pry bar, it is possible to disengage, or pop, the retaining clip 32 located in proximity of that opening 161; from its respective retaining cap 31. The same procedure may then be followed by the remaining opening 16b to disengage the retaining clip 32 located in proximity of that opening 16b from its respective cap 31. Then, the other two remaining retaining clips 32 may be disengaged from their respective retaining caps 31 by merely pulling the inner housing panel 16 away from the outer housing panel 17.

Thus, although the present invention has been shown and described with reference to a particular embodiment, for example, concealed retaining means including four retaining clips and their respective retaining caps, nevertheless, various changes and modifications obvious to a person skilled in the art to which the invention pertains, for example, other concealed retaining means having secure and certain retention capabilities, are deemed to lie within the spirit, scope and contemplation of the invention as set forthin the appended claims.

What is claimed is:

1. A microwave oven door comprising:

a first housing panel unit having an outer side and an inner side;

first retaining means mounted on said inner side of said first housing panel unit, said first retaining means comprising a plurality of studs and a like plurality of retaining caps mounted on said plurality of studs; a second housing panel unit having an outer side and an inner side; and second retaining means mounted on said inner side of said second housing panel unit, said second retaining means comprising a plurality of screws equal in number to said plurality of studs of said first retaining means, a like plurality of retaining clips respectively mounted on said plurality of screws and retained on said plurality of screws by a like plurality of nuts, said retaining clips adapted to engage said retaining caps of said first retaining means for securing said first housing panel unit to said second housing panel unit.

2. A microwave oven door as recited in claim 1 wherein said plurality of studs of said first retaining means has respective first ends and respective second ends, said respective first ends of said plurality of studs are mounted to said inner side of said first housing panel unit and said like plurality of retaining caps is respectively mounted on said respective second ends of said plurality of studs of said first retaining means.

3. A microwave oven door as recited in claim 1 wherein said plurality of screws of said second retaining means has respective first ends and respective second ends, said respective first ends of said plurality of screws are mounted to said inner side of said second housing panel unit, said plurality of retaining clips has respective first ends and respective second ends, said respective first ends of said retaining clips have respective openings therein to allow said respective plurality of retaining clips to be mounted on said plurality of screws so that said respective first ends of said plurality of retaining clips abut said inner panel of said second housing panel unit and said like plurality of nuts is mounted on said plurality of screws to retain said respective first ends of said plurality of retaining clips on said plurality of screws, and said respective second ends of said plurality of retaining clips extend beyond said respective second ends of said plurality of screws when said plurality of retaining clips is mounted on said plurality of screws, and said respective second ends of said retaining means are adapted to engage said retaining caps of said first retaining means for securing said first housing panel unit to said second housing panel unit.

4. A microwave oven door as recited in claim 1 wherein:

said plurality of studs of said first retaining means has respective first ends and respective second ends, 'said respective first ends of said plurality of studs are mounted to said inner side of said first housing panel unit and said like plurality of retaining caps is respectively mounted on said respective second ends of said plurality of studs of said first retaining means; and said plurality of screws of said second retaining means has respective first ends and respective second ends, said respective first ends of said plurality of screws are mounted to said inner side of said second housing panel unit, said plurality of retaining clips has respective first ends and respective second ends, said respective first ends of said retaining clips have respective openings therein to allow said respective plurality of retaining clips to be mounted on said plurality of screws so that said respective first ends of said plurality of retaining clips abut said inner panel of said second housing panel unit and said like plurality of nuts is mounted on said plurality of screws to retain said respective first ends of said plurality of retaining clips on said plurality of screws, and said respective second ends of said plurality of retaining clips extend beyond said respective second ends of said plurality of screws when said plurality of retaining clips is mounted on said plurality of screws, and said respective second ends of said retaining means adapted to engage said retaining caps of said first retaining means for securing said first housing panel unit to said second housing panel unit. 5. A microwave oven door as recited in claim 1 wherein:

said plurality of studs includes at least four studs; said like plurality of retaining caps includes at least four retaining caps; said plurality of screws includes at least four screws; said plurality of retaining clips includes at least four retaining clips; and said plurality of nuts includes at least four nuts.

Ii i i I! 

1. A microwave oveN door comprising: a first housing panel unit having an outer side and an inner side; first retaining means mounted on said inner side of said first housing panel unit, said first retaining means comprising a plurality of studs and a like plurality of retaining caps mounted on said plurality of studs; a second housing panel unit having an outer side and an inner side; and second retaining means mounted on said inner side of said second housing panel unit, said second retaining means comprising a plurality of screws equal in number to said plurality of studs of said first retaining means, a like plurality of retaining clips respectively mounted on said plurality of screws and retained on said plurality of screws by a like plurality of nuts, said retaining clips adapted to engage said retaining caps of said first retaining means for securing said first housing panel unit to said second housing panel unit.
 2. A microwave oven door as recited in claim 1 wherein said plurality of studs of said first retaining means has respective first ends and respective second ends, said respective first ends of said plurality of studs are mounted to said inner side of said first housing panel unit and said like plurality of retaining caps is respectively mounted on said respective second ends of said plurality of studs of said first retaining means.
 3. A microwave oven door as recited in claim 1 wherein said plurality of screws of said second retaining means has respective first ends and respective second ends, said respective first ends of said plurality of screws are mounted to said inner side of said second housing panel unit, said plurality of retaining clips has respective first ends and respective second ends, said respective first ends of said retaining clips have respective openings therein to allow said respective plurality of retaining clips to be mounted on said plurality of screws so that said respective first ends of said plurality of retaining clips abut said inner panel of said second housing panel unit and said like plurality of nuts is mounted on said plurality of screws to retain said respective first ends of said plurality of retaining clips on said plurality of screws, and said respective second ends of said plurality of retaining clips extend beyond said respective second ends of said plurality of screws when said plurality of retaining clips is mounted on said plurality of screws, and said respective second ends of said retaining means are adapted to engage said retaining caps of said first retaining means for securing said first housing panel unit to said second housing panel unit.
 4. A microwave oven door as recited in claim 1 wherein: said plurality of studs of said first retaining means has respective first ends and respective second ends, said respective first ends of said plurality of studs are mounted to said inner side of said first housing panel unit and said like plurality of retaining caps is respectively mounted on said respective second ends of said plurality of studs of said first retaining means; and said plurality of screws of said second retaining means has respective first ends and respective second ends, said respective first ends of said plurality of screws are mounted to said inner side of said second housing panel unit, said plurality of retaining clips has respective first ends and respective second ends, said respective first ends of said retaining clips have respective openings therein to allow said respective plurality of retaining clips to be mounted on said plurality of screws so that said respective first ends of said plurality of retaining clips abut said inner panel of said second housing panel unit and said like plurality of nuts is mounted on said plurality of screws to retain said respective first ends of said plurality of retaining clips on said plurality of screws, and said respective second ends of said plurality of retaining clips extend beyond said respective second ends of said plurality of screws wheN said plurality of retaining clips is mounted on said plurality of screws, and said respective second ends of said retaining means adapted to engage said retaining caps of said first retaining means for securing said first housing panel unit to said second housing panel unit.
 5. A microwave oven door as recited in claim 1 wherein: said plurality of studs includes at least four studs; said like plurality of retaining caps includes at least four retaining caps; said plurality of screws includes at least four screws; said plurality of retaining clips includes at least four retaining clips; and said plurality of nuts includes at least four nuts. 